GB1566055A

GB1566055A - Safety footwear

Info

Publication number: GB1566055A
Application number: GB6587/77A
Authority: GB
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1977-02-17
Filing date: 1977-02-17
Publication date: 1980-04-30
Also published as: FR2380750A1; PT67664A; DE7804659U1; IT7820352A0; PT67664B; NL7800998A; FR2380750B1; DE2806659A1

Description

(54) SAFETY FOOTWEAR (71) We, DUNLOP LIMITED, an English Company of Dunlop House, Ryder Street, St. James's, London SW1 do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to safety footwear and in particular to moulded footwear incorporating a metal toe cap and a metal midsole.

Safety footwear incorporating a metal toe cap and a metal midsole is well known and moulded rubber boots and shoes incorporating these safety features have been available for a considerable time. In safety footwear having these features it is desirable that the metal toe cap and metal midsole are separate.

Although it is normal for the midsole to extend underneath the toe cap, not only should they not be integral but they should not be permanently attached together by welding or mechanical means in the product.

Thus, although they may be in contact, they should be readily separable. In fact, this separation of the two metal parts is necessary in order to meet the British Standard Specification (BS 1870 Part 2 - 1976), which specifies that "there shall be no attachment between a toe cap and any protective midsole ". This provides an additional safety feature in that it will be possible to cut the footwear into two parts, should it prove necessary, along the plane between toe cap and midsole.

In the manufacture of moulded rubber safety footwear it is conventional practice to provlde a layer of uncured rubber between the toe cap and midsole and thereby to utilise the natural tack of the uncured rubber to retain the metal toe cap and metal midsole in their correct relative positions during the moulding operation, e.g. in the moulding of the sole to the upper, and to locate the midsole on a pin (or pins) on the moulding tree (last). However, in the manufacture of moulded polymeric, e.g. plastics, footwear with which the present invention is particularly concerned, which may be polymeric material having no natural 'wrack" which can be utilised, and since the toe of the moulding tree may be pointing downwards, a toe cap alone would fall off the tree.Since welding or mechanical attachment of toe cap to midsole must be avoided, this presents difficulties in accurately locating and retaining the toe cap and midsole in their relative positions during the moulding operation. The present invention provides a means of overcoming this difficulty whilst still resulting in a product in which toe cap and midsole are separate and are effectively joined by virtue only of the polymeric matrix of the footwear.

Accordingly, m one aspect, the invention provides a method of making moulded safety footwear in which at least two holes are formed in each of a metal toe cap and a metal midsole, whereby at least two pairs of holes are formed in correspondence through both toe cap and midsole when they are in their desired relative positions for the finished footwear, inserting a severable rivet of rubber of plastics material in each pair of corresponding holes to hold the toe cap and midsole together and then moulding on an outsole and upper.

The outsole and upper are preferably moulded from a thermoplastics, polymeric material or a cross-linked polyurethane such as a reaction injection moulded polyurethane.

In another aspect the invention provides moulded safety footwear having a polymeric upper and a polymeric outsole and incorporating a metal toe cap and a metal midsole, the toe cap and midsole having at least two pairs of holes in correspondence through both toe cap and midsole and a severable rivet of rubber or plastics material being positioned in each pair of corresponding holes.

The rivets are preferably of plastics material. The material of the rivet should be such that it can be forced as a "spring-fit" into a relatively small diameter hole and will thereby hold the toe cap and midsole in fixed disposition to each other. It must also be possible to cut through the rivet with a sharp knife so that the requirement of severability between toe cap and midsole is met.

In a preferred embodiment the footwear is injection moulded from poly (vinyl chloride) - (p v c) - and the rivets are also of p v c. If desired a more flexible p v c may be used for the upper than for the outsole of the footwear.

The metal midsole and toe cap may be coated with suitable agents to protect against rust and to promote bonding to the polymeric material of the upper and outsole. For example, nitrile cements are particularly useful for promoting bonding between the metal and p v c. The metal is usually degreased prior to applying the coating of cement.

The toe cap and midsole are preferably made of steel and two different types of steel may be used, one for the toe cap and one for the midsole. This is quite conventional practice and requirements of the components are described in, for example, the British Standard Specification No 1 870 and in DIN 4843.

The toe cap will normally have an in- wardly-extending flange or lip around its periphery which is to lie immediately above the midsole. The toe cap holes for the rivets can conveniently therefore be formed in this flange. Two holes, one on each side of the toe cap, may be found to be sufficient especially if they are located towards the rear, i.e. the widest part of the toe cap.

It may prove necessary to provide the riveted toe cap and midsole assembly with means to positively retain it in the desired position in the mould during the molding-on of the outsole and upper. This is particularly so where injection moulding is used, as the pressure of the injected material could easily displace the assembly and result in a faulty moulding. Thus in one specific moulding technique, the top cap/midsole assembly is attached to the last of a mould be means of a hook or pin on the last and a corresponding hole in the midsole. This hole may conveniently be located at the heel end of the midsole. Other retaining means, e.g.

magnets will be readily apparent to those skilled in the art.

The invention is further described with reference to the accompanying drawings in which: Figure 1 is a perspective view with part cut away of a metal toe cap and a metal midsole held in their desired relative posi tions by rivets; Figure 2 is a fragmentary-sectional view along line II-II of Figure 1, and Figure 3 is an enlargment of one form of rivet that can suitably be used.

In Figure 1 metal toe cap 10 is of con ventional toe cap shape with an inwardlyextending flange 11 running around its lower periphery, i.e. the periphery that is to lie adjacent a metal midsole. Metal midsole 12 is positioned with the periphery of its toe portion 1 2A in contact with the flange 11 of the toe cap. Both toe cap and midsole are provided with a pair of holes, those in the toe cap being in the flange, one at each side of and near the open end of the toe cap.

Those in the midsole are positioned to lie in registration, i.e. correspondence, with those in the toe cap when the two parts are in their desired relative positions. Rivets 14 and 15 have been pressed into the registered pairs of holes to hold toe cap and midsole in those desired relative positions.

The heel portion 12B of the midsole is provided with a hole 13 which can be used to positively locate the toe cap/midsole assembly in a mould during the moulding on of an upper and outsole.

An enlarged rivet 16 is shown in Figure 3. It is an integral moulding of pvc and has a head portion 17 designed to mate with the underface of a metal midsole and a central body portion 18. Body portion 18 is in the form of a series of four truncated cone sections 19, the base of each cone being nearer the head of the rivet than the truncated top of each cone. This shape enables the rivet to be easily sprung into position in a pair of holes in toe cap and midsole whilst ensuring a sufficiently tight fit so that the desired relative positions are maintained during subsequent moulding stages.

It will be appreciated that the footwear of the invention can incorporate conventional linings and fittings, for example, vamps, puffs and inner soles.

WHAT WE CLAIM IS: 1. A method of making moulded safety footwear in which at least two holes are formed in each of a metal toe cap and a metal midsole, whereby at least two pairs of holes are formed in correspondence through both toe cap and midsole when they are in their desired relative positions for the finished footwear, inserting a sever able rivet of rubber or plastics material in each pair of corresponding holes to hold the toe cap and midsole together and then moulding on an outsole and upper.

2. A method according to Claim 1, in which the outsole and upper are injectionmoulded around the riveted toe cap and midsole assembly.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. rivet of rubber or plastics material being positioned in each pair of corresponding holes. The rivets are preferably of plastics material. The material of the rivet should be such that it can be forced as a "spring-fit" into a relatively small diameter hole and will thereby hold the toe cap and midsole in fixed disposition to each other. It must also be possible to cut through the rivet with a sharp knife so that the requirement of severability between toe cap and midsole is met. In a preferred embodiment the footwear is injection moulded from poly (vinyl chloride) - (p v c) - and the rivets are also of p v c. If desired a more flexible p v c may be used for the upper than for the outsole of the footwear. The metal midsole and toe cap may be coated with suitable agents to protect against rust and to promote bonding to the polymeric material of the upper and outsole. For example, nitrile cements are particularly useful for promoting bonding between the metal and p v c. The metal is usually degreased prior to applying the coating of cement. The toe cap and midsole are preferably made of steel and two different types of steel may be used, one for the toe cap and one for the midsole. This is quite conventional practice and requirements of the components are described in, for example, the British Standard Specification No 1 870 and in DIN 4843. The toe cap will normally have an in- wardly-extending flange or lip around its periphery which is to lie immediately above the midsole. The toe cap holes for the rivets can conveniently therefore be formed in this flange. Two holes, one on each side of the toe cap, may be found to be sufficient especially if they are located towards the rear, i.e. the widest part of the toe cap. It may prove necessary to provide the riveted toe cap and midsole assembly with means to positively retain it in the desired position in the mould during the molding-on of the outsole and upper. This is particularly so where injection moulding is used, as the pressure of the injected material could easily displace the assembly and result in a faulty moulding. Thus in one specific moulding technique, the top cap/midsole assembly is attached to the last of a mould be means of a hook or pin on the last and a corresponding hole in the midsole. This hole may conveniently be located at the heel end of the midsole. Other retaining means, e.g. magnets will be readily apparent to those skilled in the art. The invention is further described with reference to the accompanying drawings in which: Figure 1 is a perspective view with part cut away of a metal toe cap and a metal midsole held in their desired relative posi tions by rivets; Figure 2 is a fragmentary-sectional view along line II-II of Figure 1, and Figure 3 is an enlargment of one form of rivet that can suitably be used. In Figure 1 metal toe cap 10 is of con ventional toe cap shape with an inwardlyextending flange 11 running around its lower periphery, i.e. the periphery that is to lie adjacent a metal midsole. Metal midsole 12 is positioned with the periphery of its toe portion 1 2A in contact with the flange 11 of the toe cap. Both toe cap and midsole are provided with a pair of holes, those in the toe cap being in the flange, one at each side of and near the open end of the toe cap. Those in the midsole are positioned to lie in registration, i.e. correspondence, with those in the toe cap when the two parts are in their desired relative positions. Rivets 14 and 15 have been pressed into the registered pairs of holes to hold toe cap and midsole in those desired relative positions. The heel portion 12B of the midsole is provided with a hole 13 which can be used to positively locate the toe cap/midsole assembly in a mould during the moulding on of an upper and outsole. An enlarged rivet 16 is shown in Figure 3. It is an integral moulding of pvc and has a head portion 17 designed to mate with the underface of a metal midsole and a central body portion 18. Body portion 18 is in the form of a series of four truncated cone sections 19, the base of each cone being nearer the head of the rivet than the truncated top of each cone. This shape enables the rivet to be easily sprung into position in a pair of holes in toe cap and midsole whilst ensuring a sufficiently tight fit so that the desired relative positions are maintained during subsequent moulding stages. It will be appreciated that the footwear of the invention can incorporate conventional linings and fittings, for example, vamps, puffs and inner soles. WHAT WE CLAIM IS:

1. A method of making moulded safety footwear in which at least two holes are formed in each of a metal toe cap and a metal midsole, whereby at least two pairs of holes are formed in correspondence through both toe cap and midsole when they are in their desired relative positions for the finished footwear, inserting a sever able rivet of rubber or plastics material in each pair of corresponding holes to hold the toe cap and midsole together and then moulding on an outsole and upper.

3. A method according to Claim 1 or 2

in which the toe cap and midsole are coated with a nitrile cement prior to moulding on the outsole and upper.

4. A method according to Claim 1, 2 or 3, in which the holes in the toe cap are formed in an inwardly-extending flange around the periphery of the toe cap which is to lie adjacent the midsole.

5. A method according to any one of the preceding claims, in which means are provided to positively retain the riveted toe cap/midsole assembly in the mould during the moulding on of the outsole and upper, the means comprising a hole in the mid sole and a corresponding hook or pin in the mould.

6. A method of making moulded safety footwear substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

7. Moulded safety footwear made by the method of any one of the preceding claims.

8. Moulded safety footwear having a polymeric upper and a polymeric outsole and incorporating a metal toe cap and a metal midsole, the toecap and midsole having at least two pairs of holes in correspondence through both toe cap and midsole and a severable rivet of rubber or plastics material being positioned in each pair of corresponding holes.

9. Moulded safety footwear according to Claim 8, in which the upper, outsole and rivets are all of p.v.c.

10. Moulded safety footwear according to Claim 8 or 9, in which a layer of nitrile cement is present between the metal toe cap and the upper and between the metal midsole and the outsole.

11. Moulded safety footwear according to claim 8, 9 or 10, in which the metal toe cap and midsole are made of steel.

12. Moulded safety footwear according to any one of Claims 8 to 11, in which the metal toe cap has an inwardly-extending flange around that periphery which lies adjacent the midsole, the top cap holes being in the flange.

13. Moulded safety footwear according to Claim 12, in which the two holes in the toe cap flange are one on each side of the toe cap and adjacent its rear end.

14. Moulded safety footwear according to any one of Claims 8 to 13, in which the metal midsole has an additional hole in its heel portion.